This invention relates generally to the art of energy recycling processes and apparatuses, and more particularly to an improved process and apparatus for vapor compression distillation.
A variety of processes and apparatuses utilizing vapor compression for distillation exist in the prior art. Such prior art processes and apparatuses frequently employ an evaporator chamber for creating vapor from a liquid passing therethrough. The vapor is usually compressed to enable its use as a primary source of heat in the evaporator chamber. The compressed vapor is condensed and its heat is transferred to the heated liquid by means of an indirect contact heat transfer element such as a tube bundle.
Frequently, some type of secondary method or medium is needed for cooling in distillation apparatuses. Most conventional distillation systems including vacuum distillers require methods for condensation cooling. Huge amounts of cold water or refrigeration systems are commonly used. As an environmental note, refrigeration systems using freon are not environmentally friendly and in fact it will be illegal to manufacture freon in the United States after 1995.
A variety of processes and apparatuses teaching compression of vapors from evaporated liquids are disclosed in U.S. Pat. Nos. 1,461,640; 3,109,782; 3,192,130; 3,423,293; 3,480,515; 3,488,261; 3,849,259; 3,901,768; 3,956,072; 4,082,616; 4,259,160; 4,710,272; and 4,783,242.
U.S. Pat. No. 3,488,261 discloses a vapor compression unit for removing impurities from liquids utilizing an evaporator chamber, a vapor compressor, and a power source which can also act as a heat source. A vent condenser is incorporated into the unit in the outlet portion of the manifold on the tube bundle associated with the evaporator so that uncondensed vapors exiting from the tube bundle of the evaporator pass immediately over the vent condenser to further condense the vapors prior to exhausting the uncondensed vapors and non-condensable ones to the atmosphere. An exhaust gas boiler is also included in the evaporator chamber and exhaust gases from the power source are used to generate additional vapors for the system.
Methods for recycling energy in counterflow heat exchange and distillation are disclosed in U.S. Pat. Nos. 4,671,856 and 4,769,113. U.S. Pat. No. 4,671,856 teaches a method of producing a concentrate and a distillate from a given feed material which is at least in part liquid, comprising providing a vertically extending boiling chamber and a vertically extending condensing chamber on opposite sides of a vertically extending plate member which includes a specific boiling surface on one side thereof and a condensing surface on an opposite side thereof. The plate member is sufficiently thermally conductive and sufficiently thin to conduct heat across the two surfaces relatively efficiently. A continuous feed supply is replenished into the boiling chamber so that the boiling chamber is filled with feed material to a level which entirely covers the boiling surface when the feed material is caused to boil. Boiling of the feed material occurs evenly and produces a vapor from some of the feed material and a concentrate from the rest of the material. As it is formed, the concentrate is continuously directed out of the boiling chamber into a collection chamber, and the vapor is directed out of the boiling chamber and into the condensing chamber through a compression chamber where, by means of compression, the vapor is elevated in pressure by an amount not to exceed about two psi higher than the minimum required for condensation at atmospheric pressure. A portion of the vapor is directed vertically downward uniformly and evenly across the entire condensing surface of the plate member so as to cause it to condense and form a distillate thereon and at the same time, transfer its heat of condensation across the plate member to the boiling surface for aiding in boiling the feed material at the boiling surface. As distillate is formed on the condensing surface, it is continuously directed out of the condensing chamber. A second, vertically extending plate member is included in the boiling chamber and defines a surface spaced a small distance from and in confronting relationship with the common plate member such that the two plate members define a vertically extending, laterally narrow boiling chamber.
U.S. Pat. No. 4,769,013 also discloses a method of producing a concentrate and a distillate from a given feed material which is at least in part liquid; however, a spiral-shaped boiling chamber, a vertically extending spiral-shaped condensing chamber, and a spiral-shaped common plate member are utilized.
Despite the various prior art techniques utilizing vapor compression distillation, there exists much room for improvement in the art of vapor compression distillation.